1. Field of the Invention
The invention relates to a fuel injection apparatus for an internal combustion engine, which includes a fuel injection valve that injects fuel into a cylinder.
2. Description of Related Art
Japanese Patent Application Publication No. 2005-54733 (JP 2005-54733 A) describes a fuel injection apparatus including a fuel injection valve that has a multi-hole nozzle. The fuel injection apparatus according to JP 2005-54733 A uses, under a condition that a momentum of a piston is low, a characteristic that when an inter-spray distance is short and a fuel pressure is high, a fuel density in a space downstream of the multi-hole nozzle in an injection direction becomes high and a penetration of a group of fuel sprays as a whole increases.
In general, spray characteristics depend on specifications specific to each nozzle such as an injection hole shape, a spray spread angle, and an injection direction. Some of the characteristics vary depending on a fuel pressure. However, it is difficult to change the spray pattern with the fuel pressure. Namely, it is difficult to selectively form different spray patterns such as a hollow spray pattern and a solid spray pattern by changing the fuel pressure. In the hollow spray pattern, the fuel density at the central portion is lower than that outside the central portion. In the solid spray pattern, the fuel density is not significantly different between the central portion and the outside of the central portion.